/**
 * @author Ed Spencer (http://sencha.com)
 * Transition plugin for DataViews
 */
Ext.define('Ext.ux.DataView.Animated', {

    /**
     * @property defaults
     * @type Object
     * Default configuration options for all DataViewTransition instances
     */
    defaults: {
        duration: 750,
        idProperty: 'id'
    },

    /**
     * Creates the plugin instance, applies defaults
     * @constructor
     * @param {Object} config Optional config object
     */
    constructor: function (config) {
        Ext.apply(this, config || {}, this.defaults);
    },

    /**
     * Initializes the transition plugin. Overrides the dataview's default refresh function
     * @param {Ext.view.View} dataview The dataview
     */
    init: function (dataview) {
        /**
         * @property dataview
         * @type Ext.view.View
         * Reference to the DataView this instance is bound to
         */
        this.dataview = dataview;

        var idProperty = this.idProperty,
            store = dataview.store;

        dataview.blockRefresh = true;
        dataview.updateIndexes = Ext.Function.createSequence(dataview.updateIndexes, function () {
            this.getTargetEl().select(this.itemSelector).each(function (element, composite, index) {
                element.id = element.dom.id = Ext.util.Format.format("{0}-{1}", dataview.id, store.getAt(index).internalId);
            }, this);
        }, dataview);

        /**
         * @property dataviewID
         * @type String
         * The string ID of the DataView component. This is used internally when animating child objects
         */
        this.dataviewID = dataview.id;

        /**
         * @property cachedStoreData
         * @type Object
         * A cache of existing store data, keyed by id. This is used to determine
         * whether any items were added or removed from the store on data change
         */
        this.cachedStoreData = {};

        //catch the store data with the snapshot immediately
        this.cacheStoreData(store.data || store.snapshot);

        dataview.on('resize', function () {
            var store = dataview.store;
            if (store.getCount() > 0) {
                // reDraw.call(this, store);
            }
        }, this);

        dataview.store.on('datachanged', reDraw, this);

        function reDraw(store) {
            var parentEl = dataview.getTargetEl(),
                calcItem = store.getAt(0),
                added = this.getAdded(store),
                removed = this.getRemoved(store),
                previous = this.getRemaining(store),
                existing = Ext.apply({}, previous, added);

            //hide old items
            Ext.each(removed, function (item) {
                var id = this.dataviewID + '-' + item.internalId;
                Ext.fly(id).animate({
                    remove: false,
                    duration: duration,
                    opacity: 0,
                    useDisplay: true,
                    callback: function () {
                        Ext.fly(id).setDisplayed(false);
                    }
                });
            }, this);

            //store is empty
            if (calcItem == undefined) {
                this.cacheStoreData(store);
                return;
            }

            this.cacheStoreData(store);

            var el = Ext.get(this.dataviewID + "-" + calcItem.internalId);

            //if there is nothing rendered, force a refresh and return. This happens when loading asynchronously (was not
            //covered correctly in previous versions, which only accepted local data)
            if (!el) {
                dataview.refresh();
                return true;
            }

            //calculate the number of rows and columns we have
            var itemCount = store.getCount(),
                itemWidth = el.getMargin('lr') + el.getWidth(),
                itemHeight = el.getMargin('bt') + el.getHeight(),
                dvWidth = parentEl.getWidth(),
                columns = Math.floor(dvWidth / itemWidth),
                rows = Math.ceil(itemCount / columns),
                currentRows = Math.ceil(this.getExistingCount() / columns);

            //stores the current top and left values for each element (discovered below)
            var oldPositions = {},
                newPositions = {},
                elCache = {};

            //find current positions of each element and save a reference in the elCache
            Ext.iterate(previous, function (id, item) {
                var id = item.internalId,
                    el = elCache[id] = Ext.get(this.dataviewID + '-' + id);

                oldPositions[id] = {
                    top: el.getTop() - parentEl.getTop() - el.getMargin('t') - parentEl.getPadding('t'),
                    left: el.getLeft() - parentEl.getLeft() - el.getMargin('l') - parentEl.getPadding('l')
                };
            }, this);

            //make sure the correct styles are applied to the parent element
            parentEl.applyStyles({
                display: 'block',
                position: 'relative'
            });

            //set absolute positioning on all DataView items. We need to set position, left and 
            //top at the same time to avoid any flickering
            Ext.iterate(previous, function (id, item) {
                var oldPos = oldPositions[id],
                    el = elCache[id];

                if (el.getStyle('position') != 'absolute') {
                    elCache[id].applyStyles({
                        position: 'absolute',
                        left: oldPos.left + "px",
                        top: oldPos.top + "px"
                    });
                }
            });

            //get new positions
            var index = 0;
            Ext.iterate(store.data.items, function (item) {
                var id = item.internalId,
                    el = elCache[id];

                var column = index % columns,
                    row = Math.floor(index / columns),
                    top = row * itemHeight,
                    left = column * itemWidth;

                newPositions[id] = {
                    top: top,
                    left: left
                };

                index++;
            }, this);

            //do the movements
            var startTime = new Date(),
                duration = this.duration,
                dataviewID = this.dataviewID;

            var doAnimate = function () {
                var elapsed = new Date() - startTime,
                    fraction = elapsed / duration,
                    id;

                if (fraction >= 1) {
                    for (id in newPositions) {
                        Ext.fly(dataviewID + '-' + id).applyStyles({
                            top: newPositions[id].top + "px",
                            left: newPositions[id].left + "px"
                        });
                    }

                    Ext.TaskManager.stop(task);
                } else {
                    //move each item
                    for (id in newPositions) {
                        if (!previous[id]) {
                            continue;
                        }

                        var oldPos = oldPositions[id],
                            newPos = newPositions[id],
                            oldTop = oldPos.top,
                            newTop = newPos.top,
                            oldLeft = oldPos.left,
                            newLeft = newPos.left,
                            diffTop = fraction * Math.abs(oldTop - newTop),
                            diffLeft = fraction * Math.abs(oldLeft - newLeft),
                            midTop = oldTop > newTop ? oldTop - diffTop : oldTop + diffTop,
                            midLeft = oldLeft > newLeft ? oldLeft - diffLeft : oldLeft + diffLeft;

                        Ext.fly(dataviewID + '-' + id).applyStyles({
                            top: midTop + "px",
                            left: midLeft + "px"
                        }).setDisplayed(true);
                    }
                }
            };

            var task = {
                run: doAnimate,
                interval: 20,
                scope: this
            };

            Ext.TaskManager.start(task);

            //show new items
            Ext.iterate(added, function (id, item) {
                Ext.fly(this.dataviewID + '-' + item.internalId).applyStyles({
                    top: newPositions[item.internalId].top + "px",
                    left: newPositions[item.internalId].left + "px"
                }).setDisplayed(true);

                Ext.fly(this.dataviewID + '-' + item.internalId).animate({
                    remove: false,
                    duration: duration,
                    opacity: 1
                });
            }, this);

            this.cacheStoreData(store);
        }
    },

    /**
     * Caches the records from a store locally for comparison later
     * @param {Ext.data.Store} store The store to cache data from
     */
    cacheStoreData: function (store) {
        this.cachedStoreData = {};

        store.each(function (record) {
            this.cachedStoreData[record.internalId] = record;
        }, this);
    },

    /**
     * Returns all records that were already in the DataView
     * @return {Object} All existing records
     */
    getExisting: function () {
        return this.cachedStoreData;
    },

    /**
     * Returns the total number of items that are currently visible in the DataView
     * @return {Number} The number of existing items
     */
    getExistingCount: function () {
        var count = 0,
            items = this.getExisting();

        for (var k in items) {
            count++;
        }

        return count;
    },

    /**
     * Returns all records in the given store that were not already present
     * @param {Ext.data.Store} store The updated store instance
     * @return {Object} Object of records not already present in the dataview in format {id: record}
     */
    getAdded: function (store) {
        var added = {};

        store.each(function (record) {
            if (this.cachedStoreData[record.internalId] == undefined) {
                added[record.internalId] = record;
            }
        }, this);

        return added;
    },

    /**
     * Returns all records that are present in the DataView but not the new store
     * @param {Ext.data.Store} store The updated store instance
     * @return {Array} Array of records that used to be present
     */
    getRemoved: function (store) {
        var removed = [],
            id;

        for (id in this.cachedStoreData) {
            if (store.findBy(function (record) {
                return record.internalId == id;
            }) == -1) {
                removed.push(this.cachedStoreData[id]);
            }
        }

        return removed;
    },

    /**
     * Returns all records that are already present and are still present in the new store
     * @param {Ext.data.Store} store The updated store instance
     * @return {Object} Object of records that are still present from last time in format {id: record}
     */
    getRemaining: function (store) {
        var remaining = {};

        store.each(function (record) {
            if (this.cachedStoreData[record.internalId] != undefined) {
                remaining[record.internalId] = record;
            }
        }, this);

        return remaining;
    }
});
